The present invention relates to a semiconductor etching apparatus for processing a semiconductor wafer using plasma and to an analyzing apparatus.
In order to form miniaturized shapes such as those of a semiconductor device on a wafer, material is ionized (is placed in the plasma state) and the etching processing is performed for removing material on the wafer through the operation (reaction at the surface of the wafer) of the ionized material.
Because an ionization event caused by plasma involves a lightning phenomenon, an etching apparatus, which performs processing using plasma, has an optical emission spectroscope (OES) mounted thereon to monitor light emitted by plasma. Data measured by an optical emission spectroscope is hereinafter called OES data.
OES data is composed of a plurality of wavelengths and the values of light emission intensity measured at points in time. Because there are several thousand of wavelengths, the problem is that a wavelength to be analyzed must be selected from such a large number of wavelengths.
As a method for identifying a wavelength to be analyzed, the methods described in Japanese Patent No. 3179997 (corresponding to U.S. Pat. No. 5,546,322) and Japanese Patent No. 4086190 are known. Japanese Patent No. 3179997 describes a method in which a plurality of specified elements (atom, ion, compound, etc.) is made to correspond to each wavelength of an emitted light generated by the plasma processing and this correspondence is displayed to an analyzer. Based on the elements displayed in this correspondence, the analyzer determines a wavelength and finds the correlation between the value of the emitted light at the wavelength and the etching processing result.
Japanese Patent No. 4086190 describes a method in which, for a specified wavelength, an element that is the cause of light emission at the specified wavelength is identified.
To do so, the analyzer first identifies a wavelength, related to the etching processing result, using some method and, after that, uses the disclosed method to find an element related to the etching processing result.